He designed and built a short-range missile during Iraq's four-year hiatus from United Nations arms inspections. Inspectors who returned in late 2002, enforcing Security Council limits, ruled that the al-Samoud missile's range was not short enough. The UN team crushed the missiles, bulldozed them into a pit and entombed the wreckage in concrete. "It was as if they were killing my sons," Tamimi said.

But Tamimi, 47, had other brainchildren, and these stayed secret. Concealed away from his Karama Co. factory in Baghdad were concept drawings and computations for a family of much more capable missiles, designed to share parts and features with the declared al-Samoud. The largest was meant to fly six times farther.

"This was hidden during the UNMOVIC visits," Tamimi said, referring to inspectors from the UN Monitoring, Verification and Inspection Commission. "It was forbidden for us to reveal this information."

Tamimi's covert work, which he recounted publicly for the first time in five hours of interviews last month, offers fresh perspective on the question that led the United States, Britain and Australia to war. Iraq flouted a legal duty to report the designs. The weapons they depicted, however, did not exist. After years of development - against significant obstacles - they might have taken form as nine-tonne missiles. In March they fitted in Tamimi's pocket, on two digital compact discs.

The nine-month record of arms investigators since the fall of Baghdad includes discoveries of other concealed arms research, mostly less advanced. Iraq's former government engaged in abundant deception about its ambitions and, in some cases, early steps towards development or production. Interviews with Iraqi weaponeers and US and British investigators turned up unreported records, facilities and materials that could have been used in unlawful weapons.

But investigators have found no support for the two main fears expressed in Washington and London before the war: that Iraq had a hidden arsenal of old weapons and had built advanced programs for new ones. In public statements and unauthorised interviews, investigators said they had discovered no work on old germ war agents such as anthrax and no work on a new pathogen - combining pox virus and snake venom - that led US scientists on a highly classified hunt for several months.

The investigators assess that Iraq did not, as claimed in Washington and London, resume production of its most lethal nerve agent, VX, or learn to make it last longer in storage. And they have found the former nuclear weapons program - described as a "grave and gathering danger" by President George Bush and a "mortal threat" by Vice-President Dick Cheney - in much the same shattered state as UN inspectors left it in the 1990s.

A review of evidence, including some not known to coalition investigators and some not made public, portrays a nonconventional arms establishment less capable than US analysts judged before the war.

Leading figures in Iraqi science and industry, supported by observations on the ground, described factories and institutes thoroughly beaten down by 12 years of conflict, arms embargo and economic sanctions. The remnants of Iraq's biological, chemical and missile infrastructures were riven by internal strife, bled by schemes for personal gain and handicapped by deceit along lines of command.

The broad picture emerging from the investigation to date suggests that, whatever its desire, Iraq did not possess the wherewithal to build a forbidden armoury on anything like the scale it had before the 1991 Gulf War.

David Kay, who directs the weapons hunt on behalf of the Bush Administration, reported no discoveries last year of finished weapons, bulk agents or ready-to-start production lines. Members of his Iraq Survey Group, in unauthorised interviews, said the group held out little prospect of such a find.

Some researchers at Baghdad University's College of Science - such as immunologist Alice Krikor Melconian, the chairwoman of the biotechnology department - and other elite institutions remain under scrutiny in part because investigators deem them capable of doing dangerous biological research. Investigators said they were casting a wide net at Iraq's "centres of scientific excellence".

Kay's Iraq Survey Group, which has numbered up to 1400 personnel from the Defence Department, US laboratories and intelligence agencies, is looking for biological weapons far more dangerous than those of Iraq's former arsenal.

A US National Intelligence Estimate, published October 2002, said "chances are even" that Iraqi weaponeers were working with smallpox, one of history's mass killers.

A scientific assessment panel known as Team Pox returned home in July without finding reason to believe Iraq possessed the variola virus, which causes smallpox. Even so, interviews with Iraqi scientists led to a redoubled search for work on animal poxes, harmless to humans but potentially useful as substitutes for smallpox in weapons research.

According to an informed account of the debriefing of Rihab Taha, a British-educated biologist known in the west as Dr Germ, she acknowledged receiving an order in 1990 to develop a biological weapon based on a virus. That same year, virologist Hazem Ali began research on camelpox.

There is no corresponding record, however, that Iraq had the capability or made the effort to carry out such an intent.

Taha, according to the same debriefing account, said Iraq had no access to smallpox. Ali's research halted after 45 days, with the August 1990 outbreak of war in Kuwait, and did not resume. And Taha, like all those in custody, continues to assert that biowar programs ceased entirely the following year.

Late last month, fresh evidence emerged on an old question about Iraq's illegal arms: Did the Baghdad government, as it said, rid itself of all the biological arms it produced before 1991?

The new evidence appears to be an Iraqi government record of a pivotal moment in Baghdad's long struggle to shield arms programs from outside scrutiny. Written just after the defection of Saddam Hussein's son-in-law in 1995, the document anticipates the collapse of cover stories for undisclosed weapons.

The defection of Hussein Kamel, who controlled Baghdad's Military Industrial Commission, was a turning point in the UN-imposed disarmament of Iraq in the 1990s. He told his Western debriefers about major programs in biological and nuclear weaponry that had gone undetected or unconfirmed. Iraq was forced to acknowledge what he exposed.

A handwritten Iraqi damage report, written by Hossam Amin, the head of Iraq's National Monitoring Directorate who liaised with inspectors, made an unambiguous report that Iraq destroyed its entire inventory of biological weapons.

Amin reminded Saddam's son Qusay of the government's claim that it possessed no such arms after 1990, then wrote that in truth "destruction of the biological weapons agents took place in the summer of 1991".

It was those weapons to which Secretary of State Colin Powell referred in the Security Council last February when he said, for example, that Iraq still had an estimated 8500 to 25,000 litres of anthrax.

A prewar US intelligence report that said Iraq had weapons of mass destruction was based on 15 years of information, and the hunt should continue, a senior US intelligence official has said.

Stuart Cohen, vice-chairman of the National Intelligence Council, which produced the October 2002 National Intelligence Estimate report on banned weapons, said he was not surprised stockpiles of weapons had not been found.

"I believe that our work was well-grounded. We know he (Saddam) had it, he used it, you don't unlearn that."